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- Title
A 3D Monte Carlo method for estimation of patient-specific internal organs absorbed dose for <sup>99m</sup> Tc-hynic-Tyr <sup>3</sup> -octreotide imaging.
- Authors
Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed; Parach, Ali; Ghorbani, Mahdi; Asl, Ruhollah
- Abstract
Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of 99m Tc-hydrazinonicotinamide (hynic)-Tyr 3 -octreotide as a SPECT radiotracer. 99m Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of 99m hynic-Tyr 3 -octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results.
- Subjects
MONTE Carlo method; SINGLE-photon emission computed tomography; POSITRON emission tomography; ABSORBED dose; INTRAVENOUS injections
- Publication
World Journal of Nuclear Medicine, 2016, Vol 15, Issue 2, p114
- ISSN
1450-1147
- Publication type
Article
- DOI
10.4103/1450-1147.174700